Hairpin winding electric machine

ABSTRACT

A three-phase electric machine includes a stator core defining slots, a terminal associated with one of the three phases, and a neutral. A first phase of hairpin windings is disposed in the core and has first and second parallel paths that are each continuous between the terminal and the neutral. The first path includes a first hairpin having a first leg disposed in a first of the slots and a second leg disposed in a second of the slots that is five slots away from the first slot. The first path further includes a second hairpin having a first leg disposed in a third of the slots and a second leg disposed in the second slot, wherein the second slot is seven slots away from the third slot.

TECHNICAL FIELD

The present disclosure relates to electric machines and morespecifically to electric machines that include hairpin windings.

BACKGROUND

Vehicles such as fully electric vehicles and hybrid-electric vehiclescontain a traction-battery assembly to act as an energy source for thevehicle. The traction battery may include components and systems toassist in managing vehicle performance and operations. The tractionbattery may also include high-voltage components, and an air or liquidthermal-management system to control the temperature of the battery. Thetraction battery is electrically connected to an electric machine thatprovides torque to driven wheels. Electric machines typically include astator and a rotor that cooperate to convert electrical energy intomechanical motion or vice versa.

SUMMARY

According to one embodiment, an electric machine includes a stator coredefining slots. Windings are disposed in the core and arranged in threephases each having at least one path including hairpins interconnectedto form a continuous circuit between a terminal and a neutral. Thehairpins of each path include a first type of hairpins each having afirst leg, a second leg, a crown connecting between the legs, anoutwardly extending twist joined to the first leg, and an inwardlyextending twist joined to the second leg, wherein the legs are spacedapart by a span of five slots. The hairpins of each path further includea second type of hairpins each having a first leg, a second leg, a crownconnecting between the legs, an inwardly extending twist joined to thefirst leg, and an outwardly extending twist joined to the second leg,wherein the legs are spaced apart by a span of seven slots.

According to another embodiment, a three-phase electric machine includesa stator core defining slots, a terminal associated with one of thethree phases, and a neutral. A first phase of hairpin windings isdisposed in the core and has first and second parallel paths that areeach continuous between the terminal and the neutral. The first pathincludes a first hairpin having a first leg disposed in a first of theslots and a second leg disposed in a second of the slots that is fiveslots away from the first slot. The first path further includes a secondhairpin having a first leg disposed in a third of the slots and a secondleg disposed in the second slot, wherein the second slot is seven slotsaway from the third slot.

According to yet another embodiment, an electric machine includes astator core defining slots having a plurality of radial pin positions.The pin positions including an inner position nearest an inner diameterof the core, an outer position nearest an outer diameter of the core,and one or more intermediate positions. The electric machine furtherincludes hairpins configured to be received in the slots. The hairpinsinclude: a first type of hairpins (first hairpins) each having a firstleg, a second leg, a crown connecting between the legs, an outwardlyextending twist joined to the first leg, and an inwardly extending twistjoined to the second leg, wherein the legs are spaced apart by a span offive slots; a second type of hairpins (second hairpins) each having afirst leg, a second leg, a crown connecting between the legs, aninwardly extending twist joined to the first leg, and an outwardlyextending twist joined to the second leg, wherein the legs are spacedapart by a span of seven slots; a third type of hairpins (thirdhairpins) each having a first leg, a second leg spaced apart from thefirst leg by a span of six slots, a crown connecting between the legs, afirst twist joined to the first leg and having a span of three slots,and a second twist joined to the second leg and having a span of 3.5slots; and a fourth type of hairpins (fourth hairpins) each having afirst leg, a second leg spaced apart from the first leg by a span of sixslots, a crown connecting between the legs, a first twist joined to thefirst leg and having a span of 3.5 slots, and a second twist joined tothe second leg and having a span of three slots. A winding is formed byinterconnecting select ones of the hairpins to form three phasesarranged in double layer with half of the slots containing only one ofthe phases and the other half of the slots containing two of the phases.Each of the phases have first and second parallel paths extendingbetween a terminal and a neutral.

The first path of a first of the phases may include a repeating patternof the hairpins connected in series to form a continuous conductorbetween the terminal and the neutral. Each repeating pattern may include(i) one of the first hairpins having the first and second legs disposedin the outer position, (ii) one of the third hairpins having the firstand second legs disposed in the intermediate positions and having thefirst twist connected to the second twist of the one of the firsthairpins, (iii) one of the fourth hairpins having the first and secondlegs disposed in the intermediate positions and having the first twistconnected to the second twist of the one of the third hairpins, (iv) oneof the second hairpins having the first and second legs disposed in theinner position and having the first twist connected to the second twistof the one of the fourth hairpins, (v) another of the fourth hairpinshaving the first and second legs disposed in the intermediate positionsand having the second twist connected to the second twist of the one ofthe second hairpins, and (vi) another of the third hairpins having thefirst and second legs disposed in the intermediate positions and havingthe second twist connected to the first twist of the another of thefourth hairpins.

The second path of the first of the phases may include a secondrepeating pattern of the hairpins connected in series to form acontinuous conductor between the terminal and the neutral. Each secondrepeating pattern may include (i) one of the second hairpins having thefirst and second legs disposed in the outer position, (ii) one of thethird hairpins having the first and second legs disposed in theintermediate positions and having the first twist connected to thesecond twist of the one of the second hairpins, (iii) one of the fourthhairpins having the first and second legs disposed in the intermediatepositions and having the first twist connected to the second twist ofthe one of the third hairpins, (iv) one of the first hairpins having thefirst and second legs disposed in the inner position and having thefirst twist connected to the second twist of the one of the fourthhairpins, (v) another of the fourth hairpins having the first and secondlegs disposed in the intermediate positions and having the second twistconnected to the second twist of the one of the first hairpins, and (vi)another of the third hairpins having the first and second legs disposedin the intermediate positions and having the second twist connected tothe first twist of the another of the fourth hairpins.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an electric machine.

FIG. 2 is a cross-sectional end view of a stator of the electricmachine.

FIG. 3 is a diagrammatical perspective view of a winding of the electricmachine with legs of the hairpins substantially shortened forillustrative purposes.

FIG. 4A is a perspective view of a first type of hairpin.

FIG. 4B is a perspective view of a second type of hairpin.

FIG. 4C is a perspective view of a third type of hairpin.

FIG. 4D is a perspective view of a fourth type of hairpin.

FIG. 5 is a magnified view of portion of FIG. 2.

FIG. 6 is a winding diagram of a U phase of the windings looking from aweld side (also known as a twist side) of the stator.

FIG. 7 is a detail view of the U-phase winding diagram showing of ablock of a first path of the U phase.

FIG. 8 is a perspective view of the windings for the block shown in FIG.7.

FIG. 9 is a detail view of the U-phase winding diagram showing of ablock of a second path of the U phase.

FIG. 10 is a winding diagram of a V phase of the windings looking fromthe weld side of the stator.

FIG. 11 is a winding diagram of a W phase of the windings looking fromthe weld side of the stator.

DETAILED DESCRIPTION

Embodiments of the present disclosure are described herein. It is to beunderstood, however, that the disclosed embodiments are merely examplesand other embodiments can take various and alternative forms. Thefigures are not necessarily to scale; some features could be exaggeratedor minimized to show details of particular components. Therefore,specific structural and functional details disclosed herein are not tobe interpreted as limiting, but merely as a representative basis forteaching one skilled in the art to variously employ the presentinvention. As those of ordinary skill in the art will understand,various features illustrated and described with reference to any one ofthe figures can be combined with features illustrated in one or moreother figures to produce embodiments that are not explicitly illustratedor described. The combinations of features illustrated providerepresentative embodiments for typical applications. Variouscombinations and modifications of the features consistent with theteachings of this disclosure, however, could be desired for particularapplications or implementations.

Referring to FIG. 1, a hairpin electric machine 20 may be used in avehicle such as a fully electric vehicle or a hybrid-electric vehicle.The electric machine 20 may be referred to as an electric motor, atraction motor, a generator, or the like. The electric machine 20 may bea permanent magnet machine, an induction machine, or the like. In theillustrated embodiment, the electric machine 20 is a three-phasealternating current (AC) machine. The electric machine 20 is capable ofacting as both a motor to propel the vehicle and as a generator such asduring regenerative braking.

The electric machine 20 may be powered by a traction battery of thevehicle. The traction battery may provide a high-voltage direct current(DC) output from one or more battery-cell arrays, sometimes referred toas battery-cell stacks, within the traction battery. The battery-cellarrays may include one or more battery cells that convert storedchemical energy to electrical energy. The cells may include a housing, apositive electrode (cathode), and a negative electrode (anode). Anelectrolyte allows ions to move between the anode and cathode duringdischarge, and then return during recharge. Terminals allow current toflow out of the cells for use by the vehicle.

The traction battery may be electrically connected to one or more powerelectronics modules. The power electronics modules may be electricallyconnected to the electric machines 20 and may provide the ability tobi-directionally transfer electrical energy between the traction batteryand the electric machine 20. For example, a typical traction battery mayprovide a DC voltage while the electric machine 20 may require athree-phase (AC) voltage. The power electronics module may include aninverter that converts the DC voltage to a three-phase AC voltage asrequired by the electric machine 20. In a regenerative mode, the powerelectronics module may convert the three-phase AC voltage from theelectric machine 20 acting as a generator to the DC voltage required bythe traction battery.

Referring to FIGS. 1 and 2, the electric machine 20 includes a housing21 that encloses the stator 22 and the rotor 24. The stator 22 is fixedto the housing 21 and includes a cylindrical core 32 having an innerdiameter 28 that defines a hole 30 and an outer diameter 29. The core 32may be formed from a plurality of stacked laminations. The rotor 24 issupported for rotation within the hole 30. The rotor 24 may includewindings or permanent magnets that interact with windings of the stator22 to generate rotation of the rotor 24 when the electric machine 20 isenergized. The rotor 24 may be supported on a driveshaft 26 that extendsthrough the housing 21. The driveshaft 26 is configured to couple with adrivetrain of the vehicle.

The stator core 32 defines slots 34 circumferentially arranged aroundthe core 32 and extending outward from the inner diameter 28. The slots34 may be equally spaced around the circumference and extend axiallyfrom a first end 36 of the core 32 to a second end 38. In theillustrated embodiment, the core 32 defines forty-eight slots and haseight poles, but the core 32 may include more or fewer slots and/orpoles in other embodiments. For example, the core 32 may defineseventy-two slots and have 12 poles. According to one embodiment, eachslot is 30 electrical degrees. The electric machine 20 may be adouble-layer machine meaning that some of the slots contain more thanone phase. In the illustrated embodiment, half of the slots contain twophases and the other half of the slots include a single phase. This isin contrast to a single-layer machine where each slot only contains asingle phase.

The slots 34 are spaced by a circumferential distance measured betweenthe center lines of two adjacent slots. This distance can be used as aunit of distance (hereinafter “a slot”) for relating and measuring othercomponents of the stator 22. The distance unit “slot” is sometimesreferred to as “slot pitch” or “slot span.”

Referring to FIGS. 2 and 3, the electric machine 20 may include hairpinwindings 40 placed in the slots 34 of the core 32. Hairpin windings arean emerging technology that improves efficiency for electric machinesused in vehicles and other applications. The hairpin windings 40 improveefficiency by providing a greater amount of stator conductors to reduceresistance of the winding 40 without encroaching into space reserved forthe electrical steel and the magnetic flux path.

One challenge with a hairpin winding is matching the electric-machinedesign to the desired torque-speed curve. An essential step in designingan electric machine is selecting the phase turn number so that thetorque-speed curve covers all required operating points. Forconventional stranded windings made of long wires connected in parallel,the desired phase turn number is selected by choosing the number ofturns per coil, the number of parallel paths, the number of poles, thenumber of slots per pole, and the number of layers. While all thesefactors are also available for hairpin windings, the limiting factorsare very different resulting in fewer feasible choices.

For example, while the possible number of poles, slots per pole, andlayers are identical between the two technologies, it is not practicalin a hairpin winding to have as many turns per coil as in a strandedwinding. Each hairpin needs to be connected to the next hairpin bywelding, soldering or the like, and needs to be bent according to aspecific shape in order to make the connection possible. This limits thenumber and size of the conductors that can be fit in a single slot.Another challenge is creating parallel circuits that are balanced andhave reasonably complex connections. Two paths are balanced if theirflux linkage is the same and the voltage is the same.

The electric machine 20 solves these and other problems withoutrequiring jumpers. A jumper is a conductor used to connect hairpins thatare adjacent in the electrical path but are not physically adjacentmaking a direct connect infeasible. A jumper does not extend through theslots and instead extends around the end face or the core. The electricmachine 20 may be a three-phase machine in which the hairpin windings 40are arranged in a U phase, a V phase, and a W phase. Each phase includesassociated hairpins conductors (also known as pins, hairpins, or barconductors) arranged in two or more parallel paths of windings. In theillustrated embodiment, each phase includes two parallel paths. Eachphase may include more or less parallel paths in other embodiments.

The hairpins are generally U-shaped with each bent to include a pair oflegs joined by a crown. The hairpins are installed in the stator core 32by inserting the legs through corresponding ones of the slots 34. All ofthe hairpins may be installed from the same end of the stator core 32,e.g., end 36, so that all of the crowns are located on one end of thestator, e.g., end 36, and the ends of the legs are located on the otherend, e.g., end 38. Once installed, the legs of the hairpins are bent toform twists that connect with the twists of other hairpins. The ends ofcorresponding twists are joined by a connection such as a weld 48. End36 may be referred to as the crown end and end 38 may be referred to asthe weld end (or twist end). The hairpins are typically made of barconductors having a rectangular cross-section, but the hairpins may havea circular or other cross-sectional shape.

The U phase may include a first path 44 and a second path 46. The paths44, 46 are balanced and in parallel. Each path may be equally disposedin the even and odd slots, e.g., path 44 has 24 legs in even slots and24 legs in odd slots. The paths are formed by a plurality ofinterconnected pins 42, that once connected, form a continuous circuit.Each of the paths includes a first end that starts at the U-phaseterminal 50 and a second end that ends to a neutral connection. In theillustrated embodiment, the electric machine 20 includes a singleneutral bar 52, but multiple neutral bars may be used in otherembodiments. The first and second paths 44, 46 connect to the neutralconnection 52 near 53. The paths 44, 46 are connected to each other atthe terminal 50, which is located near the outer diameter (OD) 29 of thestator core. The first and second paths 44, 46 start near the OD 29 ofthe stator core 32 and have terminal leads 59 (which are essentiallyextra-long twists) to connect to the terminal 50. The first and secondpaths 44, 46 may wind (advance), in a zig-zag fashion, in thecounterclockwise direction (when looking at end 38) through the slots 34and end near the OD 29 at the neutral connection 52. The first andsecond paths 44, 46 may be zig-zagged resulting in the paths onlyencircling the stator core once. This is in contrast to most hairpinmotors in which multiple stator revolutions are required to traversefrom the ID to the OD. In the illustrated embodiment, each of the pathsincludes twenty-four pins that are interconnected end-to-end to form acontinuous conductor between the terminal 50 and the neutral connection52 without the need of jumpers.

The V phase may include a first path 56 and a second path 58. The paths56, 58 are balanced and in parallel. The paths are formed by a pluralityof interconnected pins 64. Each of the paths includes a first end thatstarts at the V-phase terminal 66 and a second end that ends at theneutral connection 52 near 55. (In other embodiment, the U and V phasesmay have separate neutral bars.) The paths 56, 58 are connected to eachother at the terminal 66, which is located near the OD 29 of the statorcore. The first and second paths 56, 58 start near the OD 29 of thestator core and have terminal leads 67 to connect to the terminal 66.The first and second paths 56, 58 wind, in a zig-zag fashion, in thecounterclockwise direction through the slots 34 and end near the OD 29at the neutral connection 52. The first and second paths 56, 58 may windaround the stator core only one time, like the U-phase. In theillustrated embodiment, each of the paths 56, 58 includes twenty-fourpins that are interconnected end-to-end to form a continuous conductorbetween the terminal 66 and the neutral connection 52.

The W phase may include a first path 70 and a second path 72. The paths70, 72 are balanced and in parallel. The paths are formed by a pluralityof interconnected pins 78. Each of the paths includes a first end thatstarts at the W-phase terminal 80 and a second end that ends at theneutral connection 52 or the like. The paths 70, 72 are connected toeach other at the terminal 80, which is located near the OD 29 of thestator core. In other embodiments, the U, V, or W phase terminals may belocated near the ID 28. The first and second paths 70, 72 start near theOD 29 of the stator core and have terminal leads 82 to connect to theterminal 80. The first and second paths 70, 72 wind in thecounterclockwise direction through the slots 34 and end near the OD 29at the neutral connection 52. Thus, all of the paths of all of the phaseadvance in the same direction. The first and second paths 70, 72 maywind around the stator core, in a zig-zag fashion, only one time. In theillustrated embodiment, each of the paths includes twenty-four pins thatare interconnected end-to-end to form a continuous conductor between theterminal 80 and the neutral connection 52. The terminals 50, 66, and 80may include additional leads to connect to the inverter and receivevoltage from the inverter, which creates torque-producing current in thewinding paths causing the rotor 24 to rotate within the stator 22.

The hairpins of each of the paths may include one or more types ofhairpin. Different types of hairpins may differ in shape and/or size.The hairpins of machine 20 may include two main types: hairpins withboth twists extending inward (e.g., FIG. 4A, 4B) and pins with one twistextending outward and one twist extending inward (e.g., FIGS. 4C and4D).

Referring to FIG. 4A, an example first interior pin 90 may include afirst leg 98 joined to a second leg 100 at a vertex 102. (The pins arenot to scale and the legs are shortened for illustrative purposes.) Thevertex 102 may radially offset the legs to place the legs in differentslot positions. The vertex 102 may be formed by a twist that radiallyoffsets the legs by the dimension of one pin in the radial direction.The pins 90 may be formed from a single piece of metal such as copper,aluminum, silver, or any other electrically conductive material. Thefirst leg 98 is disposed in one of the slots 34 and the second leg 100is disposed in another of the slots 34 that is spaced apart by a span ofslots. The pins 90 may have a span equal to the number of slots perpole, which is six slots in the illustrated embodiment. Thus, if thefirst leg 98 was in Slot 1, the second leg 100 would be in Slot 7. Theleg 98 includes a straight portion 99 disposed within a slot 34 and afirst angled portion 104 that extends between the vertex 102 and thestraight portion 99. The straight portion 99 and the angled portion 104are joined at a first bend 106. The leg 98 also includes a twist 110that is angled inward at a second bend 108. The second leg 100 includesa straight portion 101 disposed within a slot 34 and a first angledportion 112 that extends between the vertex 102 and the straight portion101. The first and second angled portions 104, 112 and the vertex 102maybe collectively referred to as a crown. The straight portion 101 andthe angled portion 112 are joined at a first bend 114. The second leg100 also includes a twist 120 that is angled inward at a second bend118. The twists 110, 120 angle towards each other enabling the windingto zig-zag. The twist 110 and the twist 120 have different lengths. Thetwist 110 may have a span of 3.5 slots and the twist 120 may have a spanof 3 slots. Since the both twist 110, 120 fold back over the pin 90,rather than extending away like most hairpins, the pins 90 have arelative short overall span of 6 slots. The pin 90 may be fabricated byfirst forming the vertex 102, the first angled portions 104, 112, andtwo extended straight portions. Then, the pin 90 is installed into thestator 22 by inserting the extended straight portions into the slots 34of the stator 22. The second bends 108, 118 and the twists 110, 120 areformed after the pin 90 is installed through the slots by bending theextended legs as desired. The pins 90 may be used in radial positions 2and 3 as will be described below.

Referring to FIG. 4B, an example second interior pin 92 may include afirst leg 122 joined to a second leg 124 at a vertex 126. The vertex 126may radially offset the legs to place the legs in different slotpositions. The vertex 102 may be formed by a twist that radially offsetsthe legs by the dimension of one pin in the radial direction. The pins92 may be formed from a single piece of metal such as copper, aluminum,silver, or any other electrically conductive material. The pin 92 issimilar to pin 90 except that the twist 128 of the first leg has a spanof 3 slots and the twist 130 of the second leg 124 has a span of 3.5slots, i.e., the twists are flipped. The pins 92 may be used in radialpositions 4 and 5 as will be described below. In alternativeembodiments, the 3.5 span twists of both pins 90 and 92 can be 2.5 spantwists. In this case, the double layer winding pattern will be mirroredrelative to that shown in FIG. 6.

Referring to FIG. 4C, an example first exterior hairpin 94 may include afirst leg 132 joined to a second leg 134 at a vertex 136. (This pin maybe called a connector or a joinder pin depending upon its placement inthe winding.) The vertex 136 may be bent so that each of the legs are ina same slot position. The pins 94 may be formed from a single piece ofmetal such as copper, aluminum, silver, or any other electricallyconductive material. The first leg 132 is disposed in one of the slots34 and the second leg 134 is disposed in another of the slots 34 that isspaced apart by a span of slots. The pins 94 has a span of seven slotsin the illustrated embodiment. The leg 132 includes a twist 136 that isangled inward, and the first leg 134 includes a twist 140 that is angledoutward. That is, the twists 136, 138 extend in the same direction. Thetwist 136, 138 may have the same span, e.g., 3 slots. The pins 94 mayhave an overall span of 10 slot. The pins 94 may be used nearest the OD29 or the nearest the ID 28.

Referring to FIG. 4D, an example second exterior pin 96 may include afirst leg 140 joined to a second leg 142 at a vertex 148. (This pin maybe called a connector or a joinder pin depending upon its placement inthe winding.) The vertex 148 may be bent so that each of the legs are ina same slot position. The pins 94 may be formed from a single piece ofmetal such as copper, aluminum, silver, or any other electricallyconductive material. The first leg 140 is disposed in one of the slots34 and the second leg 142 is disposed in another of the slots 34 that isspaced apart by a span of slots. The pins 94 may has a span five slotsin the illustrated embodiment. The leg 140 includes a twist 144 that isangled inward, and the second leg 142 includes a twist 146 that isangled outward. That is, the twists 144, 146 extend in the samedirection. The twist 144, 146 may have the same span, e.g., 3 slots. Thepins 96 may have an overall span of 8 slots. The pins 96 may be usednearest the OD 29 or the nearest the ID 28.

Referring to FIGS. 2 and 5, the slots 34 are numbered 1 through 48 inthe counterclockwise direction with the odd number slots being labeledfor convenience. The slots 34 may include positions in the radialdirection, which may be referred to as radial slot positions, radialpositions, slot positions, or positions. Each position represents apin-receiving area that receives one leg of a hairpin. In theillustrated embodiment, each slot 34 has six sequential positions in aone-by-six linear arrangement, however, other arrangements arecontemplated. The number of positions may be 10 or 14 in otherembodiments. Thus, in the illustrated embodiment, each slot 34 includessix legs, one in each slot position. The positions are labeled 1 through6, with the first position being nearest the ID and the sixth positionbeing nearest the OD. Positions 1 and 6 may be referred to as exteriorpositions and positions 2-5 may be referred to interior positions. Theterm “radial slot position” is used to describe both a single positionof a single slot and to refer to the collective positions at that radiallocation of the stator core 32. (The slot positions are sometimesreferred to as radial layers as the slot positions are aligned andcollectively form concentric rings around the stator core. It isimportant to note that these radial layers refer to something differentthan the above-described single and double-layer winding arrangements,which refer to the number of phases in each slot.) In one or moreembodiments, the hairpins 90,92 are located in the interior slotpositions and the hairpins 94,96 are located in positions 1 and 6.

Referring to FIG. 5, the illustrated winding 40 is a double-layerwinding. In slot 1, only the U phase is contained therein, but, slot 2contains both the U phase and the V phase. Other slots may only containthe V phase, only contain the W phase, contain the U and W phases, orcontain the V and W phases. The shift for single to double phase mayoccur at the midpoint of the slots, e.g., slot only includes the samephase in positions 4-6 and may include a different phase in positions1-3, or vice versa.

Referring to FIG. 6, a winding diagram of the U phase is shown. In themachine 20, the paths may be wound in a repeating pattern of blocks 150.Each of the blocks may be the same, albeit shifted circumferential todifferent slots. In a 48-slot stator, the windings include four blockseach containing 12 consecutive slots. In this description, the blocks150 will be delineated at position 6, however, this is arbitrary. Eachblock 150 begins at the trailing end of the first hairpin and terminatesat the leading end of the last hairpin. The terms “leading” and“trailing” refer to the position of the component relative to thedirection of advancement through the path with the terminal beingconsidered the start and the neutral being the end. Each block mayinclude six hairpins: one hairpin 96, which is the first hairpin in path44, one hairpin 94, which is the fourth hairpin in path 44, two hairpins90, and two hairpins 92, one of which is the last hairpin. Unique tothis arrangement is that each path 44, 46 of windings traverses from theOD to the ID and back to the OD within each block 150, e.g., within aspan of 12 slots. Most winding arrangements are wound circumferentiallyand require one or more revolutions of the stator to traverse from theOD to the ID and back. This winding arrangement employees a zig-zagroute to achieve a large amount of radial displacement is a short amountof circumferential advancement. The zig-zag is created mostly by theinterior pins 90, 92, which have both twists extending inwardly. Eachblock 150 may include a pair of sub-blocks 152, 154. A sub-block refersto a collection of hairpins that traverse in one radial direction, i.e.,from the OD to the ID (sub-block 152) or form the ID to the OD(sub-block 154). In the first path 44, the hairpins 94 interconnect thesub-blocks 152 and 154 and the hairpins 96 are used to interconnectadjacent blocks 150.

Referring to FIGS. 7 and 8, the first block 150a of the first path 44begins at slot 40 with the first hairpin 156, which is an exterior pin96. An end of the twist 146 is located above slot 40 and is welded tothe last hairpin of the fourth block, which is a hairpin 90. Thetrailing leg 142 of the hairpin 156 is disposed in slot 37 and theleading leg 140 is disposed in slot 32. Both legs are disposed in thesixth position. The crown 148 of the hairpin 156 advances the path 44forward 5 slots. The twist 144 of the leading leg 140 then retards thepath 44 back 3 slots. The twist 128 of the second hairpin 158 furtherretards the path by 3 more slots to place the trailing leg 122 in thefifth position of slot 38 and the leading leg 124 in the fourth positionof slot 32. The twist 128 is joined to the first hairpin 156 by a weld160. The crown 126 of the hairpin 158 advances the path 44 forward sixslots and the twist 130 then retards the path 44 back 3.5 slots. Thetrailing twist 110 of the third hairpin 162 is welded to the secondhairpin 158 and also has a span of 3.5 slots. This places the trailingleg 98 in the third position of slot 39. The leading leg 100 of hairpin162 is disposed in the second position of slot 33 thus advancing thepath 44 six slots. The leading twist 120 of the hairpin 162 againretards the path 44 back 3 slots. The end of the twist 120 representsthe end of the sub-block 152.

The fourth pin 164, which is a joinder pin and of the type 94, isconnected between the third pin 162 (last pin of sub-block 152) and thefifth pin 166 (first pin of sub-block 154). The trailing twist 138retards the path 44 by 3 slots whereas the leading twist 136 advancesthe path 44 by 3 slots. The fourth pin 164 has the largest span betweenthe legs at 7 slots. The trailing leg 134 of the fourth pin 164 isdisposed in the first position of slot 39 and the leading leg 132 isdisposed in the first position of slot 32. The leading twist 136advances forward by 3 slots to connect to the fifth pin 166. The fifthpin 166, which is an interior pin 90, includes a trailing leg 100disposed in the second position of slot 26 and a leading leg 98 disposedin the third position of slot 32. In contrast to the sub-block 152, thehairpins of the sub-block 154 are advanced by the twists and areretarded by the crowns. The sixth pin 168, which is an interior pin 92,includes a trailing leg 124 disposed in the fourth position of slot 25and a leading leg 122 disposed in the fifth position of slot 31. Thetrailing twist 130 of the sixth pin 168 is joined to the leading twist110 of the fifth pin 166. The leading twist 128 is connected to theconnector pin of the next block 150. This pattern repeats itself aroundthe stator core 32.

Referring to FIGS. 6 and 9, the first block 150a of the second path 46begins at slot 41 with the first hairpin 174, which is an exterior pin94. An end of the twist 136 is located above slot 41 and is welded tothe last hairpin of the fourth block. The trailing leg 134 of thehairpin 174 is disposed in slot 38 and a leading leg 134 is disposed inslot 31. Both legs are disposed in the sixth position. The crown 136 ofthe hairpin 174 advances the path 46 forward 7 slots. The twist 138 thenretards the path 46 back 3 slots. The twist 128 of the second hairpin176 further retards the path by 3 more slots to place the trailing leg122 in the fifth position of slot 37 and the leading leg 124 in thefourth position of slot 31. The twist 128 is connected to the firsthairpin 174 by a weld or the like. The crown 126 of the hairpin 176advances the path 44 forward 6 slots and the twist 130 then retards thepath 44 back 3.5 slots. The trailing twist 110 of the third hairpin 178is welded to the second hairpin 158 and also has a span of 3.5 slots.This places the trailing leg 98 in the third position of slot 38. Theleading leg 100 of hairpin 178 is disposed in the second position ofslot 32 thus advancing the path 44 6 slots via the crown 102. Theleading twist 120 of the hairpin 178 again retards the path 44 back 3slots. The end of the twist 120 represents the end of the sub-block 152.

The fourth pin 180, which is a joinder pin and of the type 96, isconnected between the third pin 178 (last pin of sub-block 152) and thefifth pin 182 (first pin of sub-block 154). The trailing twist 144retards the path 46 by 3 slots whereas the leading twist 146 advancesthe path 46 by 3 slots. The fourth pin 180 has the smallest span betweenthe legs at five slots. The trailing leg 140 of the fourth pin 180 isdisposed in the first position of slot 38 and the leading leg 142 isdisposed in the first position of slot 33. The leading twist 146advances forward by 3 slots to connect to the fifth pin 182. The fifthpin 182, which is an interior pin 90, includes a trailing leg 100disposed in the second position of slot 27 and a leading leg 98 disposedin the third position of slot 33. The sixth pin 184, which is aninterior pin 92, includes a trailing leg 124 disposed in the fourthposition of slot 26 and a leading leg 122 disposed in the fifth positionof slot 32. The trailing twist 130 of the sixth pin 184 is joined to theleading twist 110 of the fifth pin 182. The leading twist 128 isconnected to the connector pin of the next block 150. This patternrepeats itself around the stator core 32.

Referring back to FIG. 6, in the illustrated embodiment, the twists ineach radial position extend from their respective legs in a samedirection and have a same slot span. For example, hairpins that havelegs in the first position have associated twists that extend clockwisewith a slot span of 3; hairpins that have legs in the second positionhave associated twists that extend counterclockwise with a slot span of3; hairpins that have legs in the third position have associated twiststhat extend clockwise with a slot span of 3.5; hairpins that have legsin the fourth position have associated twists that extendcounterclockwise with a slot span of 3.5; hairpins that have legs in thefifth position have associated twists that extend clockwise with a slotspan of 3; and hairpins that have legs in the sixth position haveassociated twists that extend counterclockwise with a slot span of 3.This in combination with the other above-described features places theto-be-connected twists adjacent to each other so that they can bedirectly joined without the need for any jumpers. This may be true forthe other phases as well.

Referring to FIGS. 10 and 11, the V and W phases of the windings 40 maybe the same as the U phase but shifted to different slots. The V phasemay be shifted over four slots in the counterclockwise direction to havethe first pin of path 56 disposed in slot 5 and 48 and to have the firstpin of path 58 disposed in slots 6 and 47. The W phase may be shiftedover eight slots from the U phase in the counterclockwise direction tohave the first pin of path 70 disposed in slot 9 and 4 and to have thefirst pin of path 72 disposed in slots 10 and 3. Please see the windingdiagrams for the remain hairpin locations.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms encompassed by the claims.The words used in the specification are words of description rather thanlimitation, and it is understood that various changes can be madewithout departing from the spirit and scope of the disclosure. Aspreviously described, the features of various embodiments can becombined to form further embodiments of the invention that may not beexplicitly described or illustrated. While various embodiments couldhave been described as providing advantages or being preferred overother embodiments or prior art implementations with respect to one ormore desired characteristics, those of ordinary skill in the artrecognize that one or more features or characteristics can becompromised to achieve desired overall system attributes, which dependon the specific application and implementation. These attributes caninclude, but are not limited to cost, strength, durability, life cyclecost, marketability, appearance, packaging, size, serviceability,weight, manufacturability, ease of assembly, etc. As such, embodimentsdescribed as less desirable than other embodiments or prior artimplementations with respect to one or more characteristics are notoutside the scope of the disclosure and can be desirable for particularapplications.

What is claimed is:
 1. An electric machine comprising: a stator coredefining slots; and windings disposed in the core and arranged in threephases each having at least one path including hairpins interconnectedto form a continuous circuit between a terminal and a neutral, whereinthe hairpins of each path include: a first type of hairpins (firsthairpins) each having a first leg, a second leg, a crown connectingbetween the legs, an outwardly extending twist joined to the first leg,and an inwardly extending twist joined to the second leg, wherein thelegs are spaced apart by a span of five slots, and a second type ofhairpins (second hairpins) each having a first leg, a second leg, acrown connecting between the legs, an inwardly extending twist joined tothe first leg, and an outwardly extending twist joined to the secondleg, wherein the legs are spaced apart by a span of seven slots; whereinat least one of the slots only has one of the phases disposed therein,and at least one of the slots has two of the phases disposed therein. 2.The electric machine of claim 1, wherein the hairpins of each pathfurther include a third type of hairpins (third hairpins) each having afirst leg, a second leg, a crown connecting between the legs, a firstinwardly extending twist joined to the first leg, and a second inwardlyextending twist joined to the second leg, wherein the legs are spacedapart by a span of six slots.
 3. The electric machine of claim 2,wherein the first and second twists of the third hairpins have differentslot spans.
 4. The electric machine of claim 3, wherein the hairpins ofeach path further include a fourth type of hairpins (fourth hairpins)each having a first leg, a second leg, a crown connecting between thelegs, a first inwardly extending twist joined to the first leg, and asecond inwardly extending twist joined to the second leg, wherein thelegs of the fourth hairpins are spaced apart by a span of six slots, andwherein, for the fourth hairpins, the first twists have a slot span of3.5 and the second twists have a slot span of 3, and wherein the secondtwists of the third hairpins are connected to the first twists of thefourth hairpins.
 5. The electric machine of claim 1, wherein the atleast one path is two parallel paths.
 6. The electric machine of claim1, wherein the hairpins of a first of the paths further include: a thirdtype of hairpins (third hairpins) each having a first leg, a second legspaced apart from the first leg by a span of six slots, a crownconnecting between the legs, a first inwardly extending twist joined tothe first leg, and a second inwardly extending twist joined to thesecond leg, wherein the first twists are connected to the firsthairpins, and a fourth type of hairpins (fourth hairpins) each having afirst leg, a second leg spaced apart from the first leg by a span of sixslots, a crown connecting between the legs, a first inwardly extendingtwist joined to the first leg, and a second inwardly extending twistjoined to the second leg, wherein the first twists of the fourthhairpins are connected to the second twists of the third hairpins, andthe second twists of the fourth hairpins are connected to the secondhairpins.
 7. The electric machine of claim 6, wherein each of the firsttwists of the third hairpins have a slot span of three, the secondtwists of the third hairpins have a slot span of 3.5, the first twistsof the fourth hairpins have a slot span of 3.5, and the second twists ofthe fourth hairpins have a slot span of three.
 8. The electric machineof claim 6, wherein each of the slots includes a plurality of radiallyarranged slot positions, and wherein the first and second legs of eachof the first hairpins are disposed in a same one of the slot positions,the first and second legs of each of the second hairpins are disposed ina same one of the slot positions, the first and second legs of each ofthe third hairpins are disposed in different ones of the slot positions,and the first and second legs of each of the fourth hairpins aredisposed in different ones of the slot positions.
 9. The electricmachine of claim 8, wherein the slot positions include six positionswith a first hairpin position being nearest an inner diameter of thestator core and a sixth hairpin position being nearest an outer diameterof the stator core, and wherein the first and second legs of each of thefirst hairpins are disposed in the sixth position, and the first andsecond legs of each of the second hairpins are disposed in the firstposition.
 10. An electric machine having three phases comprising: astator core defining slots; a terminal associated with one of the threephases; a neutral; and a first phase of hairpin windings disposed in thecore and having first and second parallel paths that are each continuousbetween the terminal and the neutral; wherein the first path includes afirst hairpin having a first leg disposed in a first of the slots and asecond leg disposed in a second of the slots that is five slots awayfrom the first slot, and a second hairpin having a first leg disposed ina third of the slots and a second leg disposed in the second slot,wherein the second slot is seven slots away from the third slot.
 11. Theelectric machine of claim 10, wherein the slots have a plurality ofradial positions, and wherein the first and second legs of the secondhairpin are disposed in a first of the radial positions, and the firstand second legs of the first hairpin are disposed in a second of theradial positions.
 12. The electric machine of claim 11, wherein thefirst radial position is nearest an outer diameter of the stator core,and the second radial position is nearest an inner diameter of thestator core.
 13. The electric machine of claim 10, wherein the firsthairpin further includes an outwardly extending twist joined to thefirst leg and an inwardly extending twist joined to the second leg, andthe second hairpin further includes an inwardly extending twist joinedto the first leg and an outwardly extending twist joined to the secondleg.
 14. The electric machine of claim 10, wherein the first pathfurther includes a third hairpin having a first leg disposed in a fourthof the slots and a second leg disposed in the second slot, wherein thesecond slot is six slots away from the fourth slot.
 15. The electricmachine of claim 14, wherein the third hairpin further includes a firstinwardly extending twist joined to the first leg and a second inwardlyextending twist joined to the second leg, and wherein the first andsecond inwardly extending twists have different slot spans.
 16. Theelectric machine of claim 15, wherein, for the third hairpin, the firsttwists have a slot span of three and the second twists have a slot spanof 3.5.
 17. The electric machine of claim 16, wherein the first pathfurther includes a fourth hairpin having a first leg disposed in thethird slot, a second leg disposed in the second slot, a third inwardlyextending twist joined to the first leg and having a slot span of 3.5and a fourth inwardly extending twist joined to the second leg andhaving a slot span of three, and wherein the second slot is six slotsaway from the third slot, and the third twist is connected to secondtwist of the third hairpin.
 18. The electric machine of claim 11,wherein the second path includes a third hairpin having a first legdisposed in the second position of a fourth of the slots and a secondleg disposed in the second position of a fifth of the slots that isseven slots away from the fourth slot, a fourth hairpin has a first legdisposed in the first position of the fourth slot and a second legdisposed in the first position of a sixth of the slots, and the fourthslot is five slots away from the sixth slot.
 19. The electric machine ofclaim 10, wherein half of the slots contain two of the three phases andthe other half of the slots contain only one of the three phases.
 20. Anelectric machine comprising: a stator core defining slots having aplurality of radial pin positions, the pin positions including an innerposition nearest an inner diameter of the core, an outer positionnearest an outer diameter of the core, and one or more intermediatepositions; hairpins configured to be received in the slots andincluding: a first type of hairpins (first hairpins) each having a firstleg, a second leg, a crown connecting between the legs, an outwardlyextending twist joined to the first leg, and an inwardly extending twistjoined to the second leg, wherein the legs are spaced apart by a span offive slots, a second type of hairpins (second hairpins) each having afirst leg, a second leg, a crown connecting between the legs, aninwardly extending twist joined to the first leg, and an outwardlyextending twist joined to the second leg, wherein the legs are spacedapart by a span of seven slots, a third type of hairpins (thirdhairpins) each having a first leg, a second leg spaced apart from thefirst leg by a span of six slots, a crown connecting between the legs, afirst twist joined to the first leg and having a span of three slots,and a second twist joined to the second leg and having a span of 3.5slots, and a fourth type of hairpins (fourth hairpins) each having afirst leg, a second leg spaced apart from the first leg by a span of sixslots, a crown connecting between the legs, a first twist joined to thefirst leg and having a span of 3.5 slots, and a second twist joined tothe second leg and having a span of three slots; and a winding formed byinterconnecting select ones of the hairpins to form three phasesarranged in double layer with half of the slots containing only one ofthe phases and the other half of the slots containing two of the phases,each of the phases having first and second parallel paths extendingbetween a terminal and a neutral.